// ASM: a very small and fast Java bytecode manipulation framework
// Copyright (c) 2000-2011 INRIA, France Telecom
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
// 3. Neither the name of the copyright holders nor the names of its
//    contributors may be used to endorse or promote products derived from
//    this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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// THE POSSIBILITY OF SUCH DAMAGE.
package cn.taketoday.context.asm;

/**
 * A visitor to visit a Java method. The methods of this class must be called in
 * the following order: ( {@code visitParameter} )* [
 * {@code visitAnnotationDefault} ] ( {@code visitAnnotation} |
 * {@code visitAnnotableParameterCount} | {@code visitParameterAnnotation}
 * {@code
 * visitTypeAnnotation} | {@code visitAttribute} )* [ {@code visitCode} (
 * {@code visitFrame} | {@code visit<i>X</i>Insn} | {@code visitLabel} |
 * {@code visitInsnAnnotation} | {@code
 * visitTryCatchBlock} | {@code visitTryCatchAnnotation} |
 * {@code visitLocalVariable} | {@code
 * visitLocalVariableAnnotation} | {@code visitLineNumber} )* {@code visitMaxs}
 * ] {@code visitEnd}. In addition, the {@code visit<i>X</i>Insn} and
 * {@code visitLabel} methods must be called in the sequential order of the
 * bytecode instructions of the visited code, {@code visitInsnAnnotation} must
 * be called <i>after</i> the annotated instruction, {@code visitTryCatchBlock}
 * must be called <i>before</i> the labels passed as arguments have been
 * visited, {@code
 * visitTryCatchBlockAnnotation} must be called <i>after</i> the corresponding
 * try catch block has been visited, and the {@code visitLocalVariable},
 * {@code visitLocalVariableAnnotation} and {@code
 * visitLineNumber} methods must be called <i>after</i> the labels passed as
 * arguments have been visited.
 *
 * @author Eric Bruneton
 */
public abstract class MethodVisitor {

  /**
   * The method visitor to which this visitor must delegate method calls. May be
   * null.
   */
  protected MethodVisitor mv;

  /**
   * Constructs a new {@link MethodVisitor}.
   */
  public MethodVisitor() {
    this(null);
  }

  /**
   * Constructs a new {@link MethodVisitor}.
   *
   * @param api
   *         the ASM API version implemented by this visitor. Must be
   *         {@link Opcodes#ASM7}.
   * @param methodVisitor
   *         the method visitor to which this visitor must delegate method
   *         calls. May be null.
   */
  public MethodVisitor(final MethodVisitor methodVisitor) {
    this.mv = methodVisitor;
  }

  // -----------------------------------------------------------------------------------------------
  // Parameters, annotations and non standard attributes
  // -----------------------------------------------------------------------------------------------

  /**
   * Visits a parameter of this method.
   *
   * @param name
   *         parameter name or null if none is provided.
   * @param access
   *         the parameter's access flags, only {@code ACC_FINAL},
   *         {@code ACC_SYNTHETIC} or/and {@code ACC_MANDATED} are allowed (see
   *         {@link Opcodes}).
   */
  public void visitParameter(final String name, final int access) {
    if (mv != null) {
      mv.visitParameter(name, access);
    }
  }

  /**
   * Visits the default value of this annotation interface method.
   *
   * @return a visitor to the visit the actual default value of this annotation
   * interface method, or {@literal null} if this visitor is not
   * interested in visiting this default value. The 'name' parameters
   * passed to the methods of this annotation visitor are ignored.
   * Moreover, exacly one visit method must be called on this annotation
   * visitor, followed by visitEnd.
   */
  public AnnotationVisitor visitAnnotationDefault() {
    if (mv != null) {
      return mv.visitAnnotationDefault();
    }
    return null;
  }

  /**
   * Visits an annotation of this method.
   *
   * @param descriptor
   *         the class descriptor of the annotation class.
   * @param visible
   *         {@literal true} if the annotation is visible at runtime.
   *
   * @return a visitor to visit the annotation values, or {@literal null} if this
   * visitor is not interested in visiting this annotation.
   */
  public AnnotationVisitor visitAnnotation(final String descriptor, final boolean visible) {
    if (mv != null) {
      return mv.visitAnnotation(descriptor, visible);
    }
    return null;
  }

  /**
   * Visits an annotation on a type in the method signature.
   *
   * @param typeRef
   *         a reference to the annotated type. The sort of this type reference
   *         must be {@link TypeReference#METHOD_TYPE_PARAMETER},
   *         {@link TypeReference#METHOD_TYPE_PARAMETER_BOUND},
   *         {@link TypeReference#METHOD_RETURN},
   *         {@link TypeReference#METHOD_RECEIVER},
   *         {@link TypeReference#METHOD_FORMAL_PARAMETER} or
   *         {@link TypeReference#THROWS}. See {@link TypeReference}.
   * @param typePath
   *         the path to the annotated type argument, wildcard bound, array
   *         element type, or static inner type within 'typeRef'. May be
   *         {@literal null} if the annotation targets 'typeRef' as a whole.
   * @param descriptor
   *         the class descriptor of the annotation class.
   * @param visible
   *         {@literal true} if the annotation is visible at runtime.
   *
   * @return a visitor to visit the annotation values, or {@literal null} if this
   * visitor is not interested in visiting this annotation.
   */
  public AnnotationVisitor visitTypeAnnotation(final int typeRef, final TypePath typePath, final String descriptor,
                                               final boolean visible) //
  {
    if (mv != null) {
      return mv.visitTypeAnnotation(typeRef, typePath, descriptor, visible);
    }
    return null;
  }

  /**
   * Visits the number of method parameters that can have annotations. By default
   * (i.e. when this method is not called), all the method parameters defined by
   * the method descriptor can have annotations.
   *
   * @param parameterCount
   *         the number of method parameters than can have annotations. This
   *         number must be less or equal than the number of parameter types in
   *         the method descriptor. It can be strictly less when a method has
   *         synthetic parameters and when these parameters are ignored when
   *         computing parameter indices for the purpose of parameter
   *         annotations (see
   *         https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.18).
   * @param visible
   *         {@literal true} to define the number of method parameters that can
   *         have annotations visible at runtime, {@literal false} to define
   *         the number of method parameters that can have annotations
   *         invisible at runtime.
   */
  public void visitAnnotableParameterCount(final int parameterCount, final boolean visible) {
    if (mv != null) {
      mv.visitAnnotableParameterCount(parameterCount, visible);
    }
  }

  /**
   * Visits an annotation of a parameter this method.
   *
   * @param parameter
   *         the parameter index. This index must be strictly smaller than the
   *         number of parameters in the method descriptor, and strictly
   *         smaller than the parameter count specified in
   *         {@link #visitAnnotableParameterCount}. Important note: <i>a
   *         parameter index i is not required to correspond to the i'th
   *         parameter descriptor in the method descriptor</i>, in particular
   *         in case of synthetic parameters (see
   *         https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.18).
   * @param descriptor
   *         the class descriptor of the annotation class.
   * @param visible
   *         {@literal true} if the annotation is visible at runtime.
   *
   * @return a visitor to visit the annotation values, or {@literal null} if this
   * visitor is not interested in visiting this annotation.
   */
  public AnnotationVisitor visitParameterAnnotation(final int parameter, final String descriptor,
                                                    final boolean visible) //
  {
    if (mv != null) {
      return mv.visitParameterAnnotation(parameter, descriptor, visible);
    }
    return null;
  }

  /**
   * Visits a non standard attribute of this method.
   *
   * @param attribute
   *         an attribute.
   */
  public void visitAttribute(final Attribute attribute) {
    if (mv != null) {
      mv.visitAttribute(attribute);
    }
  }

  /** Starts the visit of the method's code, if any (i.e. non abstract method). */
  public void visitCode() {
    if (mv != null) {
      mv.visitCode();
    }
  }

  /**
   * Visits the current state of the local variables and operand stack elements.
   * This method must(*) be called <i>just before</i> any instruction <b>i</b>
   * that follows an unconditional branch instruction such as GOTO or THROW, that
   * is the target of a jump instruction, or that starts an exception handler
   * block. The visited types must describe the values of the local variables and
   * of the operand stack elements <i>just before</i> <b>i</b> is executed.<br>
   * <br>
   * (*) this is mandatory only for classes whose version is greater than or equal
   * to {@link Opcodes#V1_6}. <br>
   * <br>
   * The frames of a method must be given either in expanded form, or in
   * compressed form (all frames must use the same format, i.e. you must not mix
   * expanded and compressed frames within a single method):
   *
   * <ul>
   * <li>In expanded form, all frames must have the F_NEW type.
   * <li>In compressed form, frames are basically "deltas" from the state of the
   * previous frame:
   * <ul>
   * <li>{@link Opcodes#F_SAME} representing frame with exactly the same locals as
   * the previous frame and with the empty stack.
   * <li>{@link Opcodes#F_SAME1} representing frame with exactly the same locals
   * as the previous frame and with single value on the stack (
   * <code>numStack</code> is 1 and <code>stack[0]</code> contains value for the
   * type of the stack item).
   * <li>{@link Opcodes#F_APPEND} representing frame with current locals are the
   * same as the locals in the previous frame, except that additional locals are
   * defined (<code>
   *             numLocal</code> is 1, 2 or 3 and <code>local</code> elements
   * contains values representing added types).
   * <li>{@link Opcodes#F_CHOP} representing frame with current locals are the
   * same as the locals in the previous frame, except that the last 1-3 locals are
   * absent and with the empty stack (<code>numLocal</code> is 1, 2 or 3).
   * <li>{@link Opcodes#F_FULL} representing complete frame data.
   * </ul>
   * </ul>
   *
   * <br>
   * In both cases the first frame, corresponding to the method's parameters and
   * access flags, is implicit and must not be visited. Also, it is illegal to
   * visit two or more frames for the same code location (i.e., at least one
   * instruction must be visited between two calls to visitFrame).
   *
   * @param type
   *         the type of this stack map frame. Must be {@link Opcodes#F_NEW}
   *         for expanded frames, or {@link Opcodes#F_FULL},
   *         {@link Opcodes#F_APPEND}, {@link Opcodes#F_CHOP},
   *         {@link Opcodes#F_SAME} or {@link Opcodes#F_APPEND},
   *         {@link Opcodes#F_SAME1} for compressed frames.
   * @param numLocal
   *         the number of local variables in the visited frame.
   * @param local
   *         the local variable types in this frame. This array must not be
   *         modified. Primitive types are represented by {@link Opcodes#TOP},
   *         {@link Opcodes#INTEGER}, {@link Opcodes#FLOAT},
   *         {@link Opcodes#LONG}, {@link Opcodes#DOUBLE}, {@link Opcodes#NULL}
   *         or {@link Opcodes#UNINITIALIZED_THIS} (long and double are
   *         represented by a single element). Reference types are represented
   *         by String objects (representing internal names), and uninitialized
   *         types by Label objects (this label designates the NEW instruction
   *         that created this uninitialized value).
   * @param numStack
   *         the number of operand stack elements in the visited frame.
   * @param stack
   *         the operand stack types in this frame. This array must not be
   *         modified. Its content has the same format as the "local" array.
   *
   * @throws IllegalStateException
   *         if a frame is visited just after another one, without any
   *         instruction between the two (unless this frame is a
   *         Opcodes#F_SAME frame, in which case it is silently ignored).
   */
  public void visitFrame(final int type, final int numLocal, final Object[] local, final int numStack,
                         final Object[] stack) //
  {
    if (mv != null) {
      mv.visitFrame(type, numLocal, local, numStack, stack);
    }
  }

  // -----------------------------------------------------------------------------------------------
  // Normal instructions
  // -----------------------------------------------------------------------------------------------

  /**
   * Visits a zero operand instruction.
   *
   * @param opcode
   *         the opcode of the instruction to be visited. This opcode is either
   *         NOP, ACONST_NULL, ICONST_M1, ICONST_0, ICONST_1, ICONST_2,
   *         ICONST_3, ICONST_4, ICONST_5, LCONST_0, LCONST_1, FCONST_0,
   *         FCONST_1, FCONST_2, DCONST_0, DCONST_1, IALOAD, LALOAD, FALOAD,
   *         DALOAD, AALOAD, BALOAD, CALOAD, SALOAD, IASTORE, LASTORE, FASTORE,
   *         DASTORE, AASTORE, BASTORE, CASTORE, SASTORE, POP, POP2, DUP,
   *         DUP_X1, DUP_X2, DUP2, DUP2_X1, DUP2_X2, SWAP, IADD, LADD, FADD,
   *         DADD, ISUB, LSUB, FSUB, DSUB, IMUL, LMUL, FMUL, DMUL, IDIV, LDIV,
   *         FDIV, DDIV, IREM, LREM, FREM, DREM, INEG, LNEG, FNEG, DNEG, ISHL,
   *         LSHL, ISHR, LSHR, IUSHR, LUSHR, IAND, LAND, IOR, LOR, IXOR, LXOR,
   *         I2L, I2F, I2D, L2I, L2F, L2D, F2I, F2L, F2D, D2I, D2L, D2F, I2B,
   *         I2C, I2S, LCMP, FCMPL, FCMPG, DCMPL, DCMPG, IRETURN, LRETURN,
   *         FRETURN, DRETURN, ARETURN, RETURN, ARRAYLENGTH, ATHROW,
   *         MONITORENTER, or MONITOREXIT.
   */
  public void visitInsn(final int opcode) {
    if (mv != null) {
      mv.visitInsn(opcode);
    }
  }

  /**
   * Visits an instruction with a single int operand.
   *
   * @param opcode
   *         the opcode of the instruction to be visited. This opcode is either
   *         BIPUSH, SIPUSH or NEWARRAY.
   * @param operand
   *         the operand of the instruction to be visited.<br>
   *         When opcode is BIPUSH, operand value should be between
   *         Byte.MIN_VALUE and Byte.MAX_VALUE. <br>
   *         When opcode is SIPUSH, operand value should be between
   *         Short.MIN_VALUE and Short.MAX_VALUE. <br>
   *         When opcode is NEWARRAY, operand value should be one of
   *         {@link Opcodes#T_BOOLEAN}, {@link Opcodes#T_CHAR},
   *         {@link Opcodes#T_FLOAT}, {@link Opcodes#T_DOUBLE},
   *         {@link Opcodes#T_BYTE}, {@link Opcodes#T_SHORT},
   *         {@link Opcodes#T_INT} or {@link Opcodes#T_LONG}.
   */
  public void visitIntInsn(final int opcode, final int operand) {
    if (mv != null) {
      mv.visitIntInsn(opcode, operand);
    }
  }

  /**
   * Visits a local variable instruction. A local variable instruction is an
   * instruction that loads or stores the value of a local variable.
   *
   * @param opcode
   *         the opcode of the local variable instruction to be visited. This
   *         opcode is either ILOAD, LLOAD, FLOAD, DLOAD, ALOAD, ISTORE,
   *         LSTORE, FSTORE, DSTORE, ASTORE or RET.
   * @param var
   *         the operand of the instruction to be visited. This operand is the
   *         index of a local variable.
   */
  public void visitVarInsn(final int opcode, final int var) {
    if (mv != null) {
      mv.visitVarInsn(opcode, var);
    }
  }

  /**
   * Visits a type instruction. A type instruction is an instruction that takes
   * the internal name of a class as parameter.
   *
   * @param opcode
   *         the opcode of the type instruction to be visited. This opcode is
   *         either NEW, ANEWARRAY, CHECKCAST or INSTANCEOF.
   * @param type
   *         the operand of the instruction to be visited. This operand must be
   *         the internal name of an object or array class (see
   *         {@link Type#getInternalName()}).
   */
  public void visitTypeInsn(final int opcode, final String type) {
    if (mv != null) {
      mv.visitTypeInsn(opcode, type);
    }
  }

  /**
   * Visits a field instruction. A field instruction is an instruction that loads
   * or stores the value of a field of an object.
   *
   * @param opcode
   *         the opcode of the type instruction to be visited. This opcode is
   *         either GETSTATIC, PUTSTATIC, GETFIELD or PUTFIELD.
   * @param owner
   *         the internal name of the field's owner class (see
   *         {@link Type#getInternalName()}).
   * @param name
   *         the field's name.
   * @param descriptor
   *         the field's descriptor (see {@link Type}).
   */
  public void visitFieldInsn(final int opcode, final String owner, final String name, final String descriptor) {
    if (mv != null) {
      mv.visitFieldInsn(opcode, owner, name, descriptor);
    }
  }

  /**
   * Visits a method instruction. A method instruction is an instruction that
   * invokes a method.
   *
   * @param opcode
   *         the opcode of the type instruction to be visited. This opcode is
   *         either INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC or
   *         INVOKEINTERFACE.
   * @param owner
   *         the internal name of the method's owner class (see
   *         {@link Type#getInternalName()}).
   * @param name
   *         the method's name.
   * @param descriptor
   *         the method's descriptor (see {@link Type}).
   */
  public void visitMethodInsn(final int opcode, final String owner, final String name, final String descriptor) {
    visitMethodInsn(opcode, owner, name, descriptor, opcode == Opcodes.INVOKEINTERFACE);
  }

  /**
   * Visits a method instruction. A method instruction is an instruction that
   * invokes a method.
   *
   * @param opcode
   *         the opcode of the type instruction to be visited. This opcode is
   *         either INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC or
   *         INVOKEINTERFACE.
   * @param owner
   *         the internal name of the method's owner class (see
   *         {@link Type#getInternalName()}).
   * @param name
   *         the method's name.
   * @param descriptor
   *         the method's descriptor (see {@link Type}).
   * @param isInterface
   *         if the method's owner class is an interface.
   */
  public void visitMethodInsn(final int opcode, final String owner, final String name, final String descriptor,
                              final boolean isInterface) //
  {
    if (mv != null) {
      mv.visitMethodInsn(opcode, owner, name, descriptor, isInterface);
    }
  }

  /**
   * Visits an invokedynamic instruction.
   *
   * @param name
   *         the method's name.
   * @param descriptor
   *         the method's descriptor (see {@link Type}).
   * @param bootstrapMethodHandle
   *         the bootstrap method.
   * @param bootstrapMethodArguments
   *         the bootstrap method constant arguments. Each argument must be an
   *         {@link Integer}, {@link Float}, {@link Long}, {@link Double},
   *         {@link String}, {@link Type}, {@link Handle} or
   *         {@link ConstantDynamic} value. This method is allowed to modify
   *         the content of the array so a caller should expect that this array
   *         may change.
   */
  public void visitInvokeDynamicInsn(final String name, final String descriptor, final Handle bootstrapMethodHandle,
                                     final Object... bootstrapMethodArguments) //
  {
    if (mv != null) {
      mv.visitInvokeDynamicInsn(name, descriptor, bootstrapMethodHandle, bootstrapMethodArguments);
    }
  }

  /**
   * Visits a jump instruction. A jump instruction is an instruction that may jump
   * to another instruction.
   *
   * @param opcode
   *         the opcode of the type instruction to be visited. This opcode is
   *         either IFEQ, IFNE, IFLT, IFGE, IFGT, IFLE, IF_ICMPEQ, IF_ICMPNE,
   *         IF_ICMPLT, IF_ICMPGE, IF_ICMPGT, IF_ICMPLE, IF_ACMPEQ, IF_ACMPNE,
   *         GOTO, JSR, IFNULL or IFNONNULL.
   * @param label
   *         the operand of the instruction to be visited. This operand is a
   *         label that designates the instruction to which the jump
   *         instruction may jump.
   */
  public void visitJumpInsn(final int opcode, final Label label) {
    if (mv != null) {
      mv.visitJumpInsn(opcode, label);
    }
  }

  /**
   * Visits a label. A label designates the instruction that will be visited just
   * after it.
   *
   * @param label
   *         a {@link Label} object.
   */
  public void visitLabel(final Label label) {
    if (mv != null) {
      mv.visitLabel(label);
    }
  }

  // -----------------------------------------------------------------------------------------------
  // Special instructions
  // -----------------------------------------------------------------------------------------------

  /**
   * Visits a LDC instruction. Note that new constant types may be added in future
   * versions of the Java Virtual Machine. To easily detect new constant types,
   * implementations of this method should check for unexpected constant types,
   * like this:
   *
   * <pre>
   * if (cst instanceof Integer) {
   *     // ...
   * }
   * else if (cst instanceof Float) {
   *     // ...
   * }
   * else if (cst instanceof Long) {
   *     // ...
   * }
   * else if (cst instanceof Double) {
   *     // ...
   * }
   * else if (cst instanceof String) {
   *     // ...
   * }
   * else if (cst instanceof Type) {
   *     int sort = ((Type) cst).getSort();
   *     if (sort == Type.OBJECT) {
   *         // ...
   *     }
   *     else if (sort == Type.ARRAY) {
   *         // ...
   *     }
   *     else if (sort == Type.METHOD) {
   *         // ...
   *     }
   *     else {
   *         // throw an exception
   *     }
   * }
   * else if (cst instanceof Handle) {
   *     // ...
   * }
   * else if (cst instanceof ConstantDynamic) {
   *     // ...
   * }
   * else {
   *     // throw an exception
   * }
   * </pre>
   *
   * @param value
   *         the constant to be loaded on the stack. This parameter must be a
   *         non null {@link Integer}, a {@link Float}, a {@link Long}, a
   *         {@link Double}, a {@link String}, a {@link Type} of OBJECT or
   *         ARRAY sort for {@code .class} constants, for classes whose version
   *         is 49, a {@link Type} of METHOD sort for MethodType, a
   *         {@link Handle} for MethodHandle constants, for classes whose
   *         version is 51 or a {@link ConstantDynamic} for a constant dynamic
   *         for classes whose version is 55.
   */
  public void visitLdcInsn(final Object value) {
    if (mv != null) {
      mv.visitLdcInsn(value);
    }
  }

  /**
   * Visits an IINC instruction.
   *
   * @param var
   *         index of the local variable to be incremented.
   * @param increment
   *         amount to increment the local variable by.
   */
  public void visitIincInsn(final int var, final int increment) {
    if (mv != null) {
      mv.visitIincInsn(var, increment);
    }
  }

  /**
   * Visits a TABLESWITCH instruction.
   *
   * @param min
   *         the minimum key value.
   * @param max
   *         the maximum key value.
   * @param dflt
   *         beginning of the default handler block.
   * @param labels
   *         beginnings of the handler blocks. {@code labels[i]} is the
   *         beginning of the handler block for the {@code min + i} key.
   */
  public void visitTableSwitchInsn(final int min, final int max, final Label dflt, final Label... labels) {
    if (mv != null) {
      mv.visitTableSwitchInsn(min, max, dflt, labels);
    }
  }

  /**
   * Visits a LOOKUPSWITCH instruction.
   *
   * @param dflt
   *         beginning of the default handler block.
   * @param keys
   *         the values of the keys.
   * @param labels
   *         beginnings of the handler blocks. {@code labels[i]} is the
   *         beginning of the handler block for the {@code keys[i]} key.
   */
  public void visitLookupSwitchInsn(final Label dflt, final int[] keys, final Label[] labels) {
    if (mv != null) {
      mv.visitLookupSwitchInsn(dflt, keys, labels);
    }
  }

  /**
   * Visits a MULTIANEWARRAY instruction.
   *
   * @param descriptor
   *         an array type descriptor (see {@link Type}).
   * @param numDimensions
   *         the number of dimensions of the array to allocate.
   */
  public void visitMultiANewArrayInsn(final String descriptor, final int numDimensions) {
    if (mv != null) {
      mv.visitMultiANewArrayInsn(descriptor, numDimensions);
    }
  }

  /**
   * Visits an annotation on an instruction. This method must be called just
   * <i>after</i> the annotated instruction. It can be called several times for
   * the same instruction.
   *
   * @param typeRef
   *         a reference to the annotated type. The sort of this type reference
   *         must be {@link TypeReference#INSTANCEOF},
   *         {@link TypeReference#NEW},
   *         {@link TypeReference#CONSTRUCTOR_REFERENCE},
   *         {@link TypeReference#METHOD_REFERENCE},
   *         {@link TypeReference#CAST},
   *         {@link TypeReference#CONSTRUCTOR_INVOCATION_TYPE_ARGUMENT},
   *         {@link TypeReference#METHOD_INVOCATION_TYPE_ARGUMENT},
   *         {@link TypeReference#CONSTRUCTOR_REFERENCE_TYPE_ARGUMENT}, or
   *         {@link TypeReference#METHOD_REFERENCE_TYPE_ARGUMENT}. See
   *         {@link TypeReference}.
   * @param typePath
   *         the path to the annotated type argument, wildcard bound, array
   *         element type, or static inner type within 'typeRef'. May be
   *         {@literal null} if the annotation targets 'typeRef' as a whole.
   * @param descriptor
   *         the class descriptor of the annotation class.
   * @param visible
   *         {@literal true} if the annotation is visible at runtime.
   *
   * @return a visitor to visit the annotation values, or {@literal null} if this
   * visitor is not interested in visiting this annotation.
   */
  public AnnotationVisitor visitInsnAnnotation(final int typeRef, final TypePath typePath, final String descriptor,
                                               final boolean visible) //
  {
    if (mv != null) {
      return mv.visitInsnAnnotation(typeRef, typePath, descriptor, visible);
    }
    return null;
  }

  // -----------------------------------------------------------------------------------------------
  // Exceptions table entries, debug information, max stack and max locals
  // -----------------------------------------------------------------------------------------------

  /**
   * Visits a try catch block.
   *
   * @param start
   *         the beginning of the exception handler's scope (inclusive).
   * @param end
   *         the end of the exception handler's scope (exclusive).
   * @param handler
   *         the beginning of the exception handler's code.
   * @param type
   *         the internal name of the type of exceptions handled by the
   *         handler, or {@literal
   *         null} to catch any exceptions (for "finally" blocks).
   *
   * @throws IllegalArgumentException
   *         if one of the labels has already been visited by this visitor (by
   *         the {@link #visitLabel} method).
   */
  public void visitTryCatchBlock(final Label start, final Label end, final Label handler, final String type) {
    if (mv != null) {
      mv.visitTryCatchBlock(start, end, handler, type);
    }
  }

  /**
   * Visits an annotation on an exception handler type. This method must be called
   * <i>after</i> the {@link #visitTryCatchBlock} for the annotated exception
   * handler. It can be called several times for the same exception handler.
   *
   * @param typeRef
   *         a reference to the annotated type. The sort of this type reference
   *         must be {@link TypeReference#EXCEPTION_PARAMETER}. See
   *         {@link TypeReference}.
   * @param typePath
   *         the path to the annotated type argument, wildcard bound, array
   *         element type, or static inner type within 'typeRef'. May be
   *         {@literal null} if the annotation targets 'typeRef' as a whole.
   * @param descriptor
   *         the class descriptor of the annotation class.
   * @param visible
   *         {@literal true} if the annotation is visible at runtime.
   *
   * @return a visitor to visit the annotation values, or {@literal null} if this
   * visitor is not interested in visiting this annotation.
   */
  public AnnotationVisitor visitTryCatchAnnotation(final int typeRef, final TypePath typePath,
                                                   final String descriptor, final boolean visible) //
  {
    if (mv != null) {
      return mv.visitTryCatchAnnotation(typeRef, typePath, descriptor, visible);
    }
    return null;
  }

  /**
   * Visits a local variable declaration.
   *
   * @param name
   *         the name of a local variable.
   * @param descriptor
   *         the type descriptor of this local variable.
   * @param signature
   *         the type signature of this local variable. May be {@literal null}
   *         if the local variable type does not use generic types.
   * @param start
   *         the first instruction corresponding to the scope of this local
   *         variable (inclusive).
   * @param end
   *         the last instruction corresponding to the scope of this local
   *         variable (exclusive).
   * @param index
   *         the local variable's index.
   *
   * @throws IllegalArgumentException
   *         if one of the labels has not already been visited by this visitor
   *         (by the {@link #visitLabel} method).
   */
  public void visitLocalVariable(final String name, final String descriptor, final String signature,
                                 final Label start, final Label end, final int index) //
  {
    if (mv != null) {
      mv.visitLocalVariable(name, descriptor, signature, start, end, index);
    }
  }

  /**
   * Visits an annotation on a local variable type.
   *
   * @param typeRef
   *         a reference to the annotated type. The sort of this type reference
   *         must be {@link TypeReference#LOCAL_VARIABLE} or
   *         {@link TypeReference#RESOURCE_VARIABLE}. See
   *         {@link TypeReference}.
   * @param typePath
   *         the path to the annotated type argument, wildcard bound, array
   *         element type, or static inner type within 'typeRef'. May be
   *         {@literal null} if the annotation targets 'typeRef' as a whole.
   * @param start
   *         the fist instructions corresponding to the continuous ranges that
   *         make the scope of this local variable (inclusive).
   * @param end
   *         the last instructions corresponding to the continuous ranges that
   *         make the scope of this local variable (exclusive). This array must
   *         have the same size as the 'start' array.
   * @param index
   *         the local variable's index in each range. This array must have the
   *         same size as the 'start' array.
   * @param descriptor
   *         the class descriptor of the annotation class.
   * @param visible
   *         {@literal true} if the annotation is visible at runtime.
   *
   * @return a visitor to visit the annotation values, or {@literal null} if this
   * visitor is not interested in visiting this annotation.
   */
  public AnnotationVisitor visitLocalVariableAnnotation(final int typeRef, final TypePath typePath,
                                                        final Label[] start, final Label[] end, final int[] index, final String descriptor,
                                                        final boolean visible) //
  {
    if (mv != null) {
      return mv.visitLocalVariableAnnotation(typeRef, typePath, start, end, index, descriptor, visible);
    }
    return null;
  }

  /**
   * Visits a line number declaration.
   *
   * @param line
   *         a line number. This number refers to the source file from which
   *         the class was compiled.
   * @param start
   *         the first instruction corresponding to this line number.
   *
   * @throws IllegalArgumentException
   *         if {@code start} has not already been visited by this visitor (by
   *         the {@link #visitLabel} method).
   */
  public void visitLineNumber(final int line, final Label start) {
    if (mv != null) {
      mv.visitLineNumber(line, start);
    }
  }

  /**
   * Visits the maximum stack size and the maximum number of local variables of
   * the method.
   *
   * @param maxStack
   *         maximum stack size of the method.
   * @param maxLocals
   *         maximum number of local variables for the method.
   */
  public void visitMaxs(final int maxStack, final int maxLocals) {
    if (mv != null) {
      mv.visitMaxs(maxStack, maxLocals);
    }
  }

  /**
   * Visits the end of the method. This method, which is the last one to be
   * called, is used to inform the visitor that all the annotations and attributes
   * of the method have been visited.
   */
  public void visitEnd() {
    if (mv != null) {
      mv.visitEnd();
    }
  }
}
